Polarity reversible rectifying circuit



April 19, 1966 c. B. VAUGHAN 3,247,445

POLARITY REVERSIBLE RECTIFYING CIRCUIT Original Filed Jan. 15, 1962 5Sheets-Sheet 1 FIG. 1

Q N INVENTOR. CARROLL B. M4UGHA N WX M April 19, 1966 c. B. VAUGHAN3,247,445

POLARITY REVERSIBLE RECTIFYING CIRCUIT Original Filed Jan. 15, 1962 3Sheets-Sheet 2 H TI'ORA/E Y April 19, 1966 c. B. VAUGHAN POLARITYREVERSIBLE RECTIFYING CIRCUIT 3 Sheets-Sheet 5 Original Filed Jan. 15,1962 FIG. 6

INVENTOR. CARROLL B. l/AUGHAN United States Patent 3 Claims. (Cl. 321-8)The present application is a division of US. application Serial No.166,224, filed January 15, 1962 by Carroll B. Vaughan and assigned toThe Bendix Corporation, and the invention relates in general to apolarity reversible rectifying circuit and more particularly to apolarity reversible rectifying circuit including novel means forreversing polarity of a direct voltage supplied at a particular channelwithout the introduction of undesirable switching transients or surgingelectric currents.

Heretofore, a number of devices were available to supply from a singlealternating current source, a plurality of independently adjustablealternating currents on a plurality of channels. These devices used aseparate auto transformer for each output channel. Or, if there was apredetermined relationship between the alternating currents to beprovided at two channels, a single auto transformer was used, with twobrushes mechanically linked together.

There may be provided, however, a multi independent brush autotransformer that provides a plurality of independently adjustablealternating currents on a plurality of channels. In the presentinvention, a plurality of rectifying circuits are attached one each, toeach output channel of the multi independent brush auto transformer torectify the alternating current output. Several of the rectifyingcircuits may include a reversing circuit, of a novel design, forreversing polarity of the direct voltage supplied at a particularchannel Without the introduction of the usual undesirable switchingtransient electric currents.

An object of the invention is in the provision of a novel polarityreversible rectifying circuit.

Another object of the invention is in the provision of a novel polarityreversible type rectifying circuit whereby the polarity of an outputvoltage may be reversed without switching transients or surging electriccurrents.

Another object of the invention is to provide a rectifying circuit of apolarity reversible type including switching means for eifecting areversal of the polarity of an output voltage together with a capacitorso arranged in operative relation therewith as to prevent surgingtransients from arising upon such polarity reversal.

These and other objects and features of the invention are pointed out inthe following description in terms of the embodiments thereof which areshown in the accompanying drawings. It is to be understood, however,that the drawings are for the purpose of illustration only and are not adefinition of the limits of the invention, reference being had to theappended claims for this purpose.

In the drawings:

FIGURE 1 is an exploded view of the operative parts of a multi variablebrush auto transformer of the present invention.

FIGURE 2 is a detailed View of a spring loaded brush and brush holder ofthe multi variable brush auto transformer shown in FIGURE 1.

FIGURE 3 is a front view of the multi variable brush auto transformer.

FIGURE 4 is a side view of one of the single brush assemblies of FIGURE3.

FIGURE 5 is a schematic drawing of a novel direct current power supplycircuit incorporating a multi variable brush auto transformer such asshown in FIGURES 1 and 3.

- FIGURE 6 is a schematic drawing showing in detail a polarity reversalswitch in the power supply circuit of FIGURE 5.

A novel direct current power supply is shown in the schematic drawingsof FIGURES 5 and 6 and incorporates a novel multi independent brush autotransformer (or alternating current power supply, two embodiments ofwhich are shown in FIGURES 1, 2, 3 and 4.

Referring to FIGURE 1, there is shown therein an exploded View of theoperative parts of the novel multi independent brush auto transformer.In particular, a toroid 201 is wound with a wire 202 in a single layerover its outside cylindrical surface so as to provide an exposedsegmental wire contact or commutator surface 203 of a wire wound toroid,as described and claimed in a copending US. application Serial No.315,735, filed September 25, 1963, by Carroll B. Vaughan as a divisionof U8. application Serial No. 166,343, filed January 15, 1962 by CarrollByrd Vaughan, now US. Patent No. 3,213,520 granted October 26, 1965, toCarroll B. Vaughan for method for preparing a toroid core, and assignedto The Bendix Corporation, assignee of the present application. In theFIGURE 1, the wire is shown covering approximately 330 of the outsidesurface.

Two ends 218, 219, of the wire 202 to be connected to an alternatingcurrent source are brought out to two terminals 220 and 221 on a toroidframe (not shown). A ring gear 222 (having an inside diameter of, forexample, approximately 3% inches, and an outside diameter of, forexample, approximately 4 /2 inches with 10 teeth per inch on its outerdiameter), fits over the toroid 201. The toroid 201 has an outsidediameter of, for example, approximately 3 inches.

A brush 223, held by a brush holder 226, makes a variable operativeelectrical contact with commutator surface 203 and is mounted in a slot224 located in the wall of the gear 222 and is capable of movingradially in the gear under the constraint of the slot 224, springloading means 225, and the brush holder 226. A detailed view of thespring loading 225, brush 22.3, and brush holder 226 is shown 'in FIGURE2. The brush 223 is, for example, approximately by V by i of an inch,and the ring gear 222 has a width, for example, of of an inch. Aflexible metal pigtail conductor 226' leads from the brush holder 226 tothe metal ring gear 222. Thus, there is a conducting path from the inputwire terminals 220 and 221, of the toroid 201 through the toroidwindings 202 and commutator surface 203 to the brush 223, brush holder226, and pigtail conductor 226 into the ring gear 222.

Ring gear 222 rides next to a wrinkle spring washer 227 made of aconducting material. A pigtail conductor 229 is soldered to the wrinklewasher 227 and brought out to a terminal lug (not shown) on the frame(not shown). An insulating ring washer 228 having the same dimension asthe ring gear 222 is then stacked next to the wrinkle spring washer 227.

What has been just described, namely the ring gear 222, brush 223,wrinkle washer 227, and insulating ring 228 comprise one of manyassemblies which are to be mounted in the multi independent brush autotransformer. In the present embodiment, 10 such assemblies are installedaround the center toroid 201. It should be noted that the multiple brushauto transformer may comprise any number of outputs, depending on thelength of the toroid 201 and the number of assemblies.

The toroid 201 is securely mounted on a rigid frame (not shown) andsurrounded by a housing (not shown). The wire 202 on the toroid 201 isconnected at its ends 3 218 and 219 to two terminals 220 and 221 mountedon the outside of the frame and housing.

The brushes 223 are positioned by rotation of the ring gear 222. Thisgear 222 is rotated by means of a worm gear 230 mounted on a shaft 231terminating in a crank 232. By revolving the crank 232, the worm gear230 causes the ring gear 222 to rotate.

The location of the brush 223 on the toroid commutator surface 203 isproportional to the number of revolutions of the crank 232 and isindicated on a flat slide rule indicator 235. A string 237 winds andunwinds with the direction of rotation of the crank 232. The string islead over a small pulley and actuates pointer 236 on the slide ruleindicator 235. A spring 239 or other restoring force returns the pointer236 to the zero position when the brush is at a minimum position. As thecrank 232 is turned, a rack and pinion arrangement advances a slottedshaft 234 with an eyelet 233 to guide the string 237, in order that thestring will not slack up on the crank shaft 232, but will lay in eventurns. There may be a plurality of such gear and brush assembly, andthere is one indicating device for each gear and brush assembly and eachslide rule indicator 235 may be calibrated in either percentages orproportional to the output voltage.

Alternative embodiment ably mounted on the shaft 247 and coaxial withthe toroid 201. Six arms, 251a through 251 of conducting material aresecurely mounted on each to the knurled wheels 250a through 250 and areso spaced that the arms can pass each other freely. Six brush holderassemblies 252a through 252 are mounted at the ends of arms 251a through251 and each contains a brush 253a through 253 Each brush 253a through253] makes an operative electrical contact with a Wire commutatorsurface 203 (or segmental surfaces of the Wire Winding) of the toroid201, with each brush making contact along a different path or track onthe wire Wound commutator surface 203. The wire wound surface 203 maybe, for example, of a commutator type.

Six electrical conductors 255a through 255 connect each conducting arm251a through 251] to six hair springs 256a through 256], made ofconducting material. Each spring is made of, for example, phosphorbronze ribbon and is enclosed in a spaghetti sleeving 258, as shown inFIGURES 3 and 4. The enclosed springs 256a through 256 are coiled aroundthe shaft 247 next to the associated wheel 250a through 250 to form aone and one quarter turn loop around the shaft when the brush 253 isrotated to, for example, a three hundred and thirty degree position; anda half open turn when the brush is in a zero degree position. Thepurpose of the phospher ribbon conductor is twofold: first, tomechanically standup under constant coiling and uncoiling, caused by thewheel 250 turning in adjustment of the output voltage; and second, to bea conductor from the brush 253 (in contact with the contact surface 203)to terminal 259 on the frame; that will not interfere with theindependent motion of the wheels 250.

The other end of each spring ribbon 256a through 256] is connected toterminals 25% through 259] on the frame 248. Thus, a multi tapindependently variable auto transformer is constructed. The number ofindependent variable taps will depend on the width of the toroid 201 andthe number of knurled wheels 250 with attached arm 253 and brush 257.

Each of the knurled wheels 250a through 250i may bear suitable indicia260a through 250], respectively, to indicate the relative position ofeach brush 253 with respect to the wire wound commutator surface 203 andfrom, for example, the zero degree position to the three hundred andthirty degree position.

DC. power supply circuit Referring to FIGURE 5, there is shown therein aschematic drawing of a novel power supply circuit using the multivariable independent brush auto transformer of, for example, the typeshown in FIGURES 1 and 2 or FIG- URES 3 and 4. Referring to FIGURE 5,and tracing the structure and operation of the powersupplysimultaneously, an electrical potential 231 which may be the VoltAC. commonly available, is applied across the input of an isolation andstep down transformer 232 which reduces the line voltage to, forexample, 36 volts. This output is fed to a conventional auto transformer283 which in turn feeds current into a multi variable tap autotransformer 234 shown as including a winding 289 and six variable outputterminals 290 through 290. The adjustable output terminals 290 through290 are connected into a rectifier circuit 285, which rectifies theoutput of the auto transformer 284 to produce six adjustable D.C.voltages available at terminals 301 through 307. In particular, there isavailable adjustable positive direct voltages, for example, of O to +50volts DC. on taps 301 and 303; and direct negative voltage, for example,of 0 to 50 volts DC. on taps 304 and 306; and continuously positive andnegative adjustable voltages, for example, of 50 to +50 D.C. volts ontaps 302 and 305. The amplitude control for each of the voltagesavailable on taps 301 to 306 is the adjuster on the multi variable autotransformer (the crank handle 232 of FIGURE 1 or knurled wheel 250 ofFIGURES 3 and 4).

The output at the first terminal 290 of the multi variable taptransformer 284 is fed into a forward biased diode 291 and then acrossan electrolytic capacitor 292 whose negative side is connected tocommon. An output terminal 301 of the power supply is connected by aconductor 301' to the juncture of the diode 291 and the electrolyticcapacitor 292 Thus, an AC. voltage from the multi tap auto transformeris adjusted in amplitude by the multi tap auto transformer 284 and thenrectified in the rectifier circuit 285.

The voltage at terminal 303 is rectified by a circuit identical to theone just described; and the voltage at taps 304 and 306 are rectified bythe same circuit with the exception that diodes 231 and 2911. and thecapacitors 292 and 292 are of reversed polarity.

In order to supply continuously variable :50 volt D.C. voltage on taps302 and 305, a switching circuit 297 and 297 is applied comprising afour pole double throw switch 295, and shown in detail in FIGURE 6. Theswitch 295 includes four pairs of connected contacts 310 and 311, 312and 313, 314 and 315, 316 and 317, and which pairs of contacts arearranged to cooperate respectively with four switch arms 320, 321, 322,and 323 of the four pole double throw switch 295. A diode 291 isconnected in the forward direction across contacts 310 and 312 while acapacitor 292 is connected across contacts 314 and 316. An outputvoltage from the multi tap auto transformer 284 is applied throughconductor 290 (290 or 290 of FIGURE 5) to the switch arm 320 of theswitch 295; while the switch arms 321 and 322 are connccted by aconductor 325 to an output conductor 300 (302' or 305' of FIGURE 5), andcontact 323 is connected to common conductor 307. Thus, as shown inFIGURE 5, the terminals 302 and 365 are connected via conductors 302'and 305, respectively, to the switch arms 321 and 322 of the receivingswitch 295 of FIGURE 6 included in the respective switching circuits2537 and 297 of FIGURE 5.

When the four pole double throw switch 295 is closed in one direction,current from the multi variable tap auto transformer 284 flows in thepositive direction across diode 291 and is stored across capacitor 292.When the switch 295 is thrown in the opposite direction, the diode 291is back biased and the capacitor 292 is reversed thus applying throughconductors 325 and 300 (conductors 302' and 305' of FIGURE 5 a negativeDC. voltage to the output terminal 302 or 305. It should be noted thatupon operation of this switch 295, there is an immediate reversal ofpolarity seen at the output terminal 302 or 305 and there is no surgetransient, because the capacitor 292 does not discharge, and thereforedoes not have to be recharged. The diode 291 will effectively controland cause the charge on the capacitor 291 to remain in the same senseirrespective of the position of the reversing switch 295. Reversal ofposition of the switch 295 will, however, reverse the polarity seen atthe output terminals 302 or 305.

Thus, the adjustable A.C. voltages available at terminal 290 and 290from the multi tap transformer 284 are fed into the two circuits 297 and297 which are similar to the circuit shown in FIGURE 6. The voltages arerectified and supplied through conductor 302' and 305' to terminals 302and 305 as a continuously variable +50 to 50 DC. voltage.

In addition to supplying a plurality of adjustable voltages, the powersupply circuit supplies output voltages having a high resolution andgreat flexibility of range because the stepdown transformer 282 and theconventional auto transformer 283 can be adjusted, thereby the rangeoutput DC. voltage available can be made large or small.

A further advantage of the DC. power supply circuit as shown is that itavoids saturating the magnetic core of the multi independent brush autotransformer 284. Each rectifier circuit (diode 291 and capacitor 292),presents a half wave load to the multi tap auto transformer 284,however, some of the half wave loads (those on terminals 290 and 290 ofthe transformer 284) are of one polarity, while the loads on theterminals 290 and 290" are of a reversed polarity. Thus, saturation ofthe magnetic core of the transformer 284 may be avoided.

The power supply circuits of FIGURES 5, 6, 7 and 8 are described andclaimed in the copending US. application Serial No. 166,224, filedJanuary 15, 1962 by Carroll B. Vaughan and assigned to The BendixCorporation, while the autotransformer of FIGURES 1, 2, 3 and 4 isdescribed and claimed in a copending US. application Serial No. 300,312,filed August 6, 1963, by Carroll 13. Vaughan as a division of the US.application Serial No. 166,224 and assigned to The Bendix Corporation.

While several embodiments of the invention have been illustrated anddescribed, various changes in the form and relative arrangements of theparts, which will now appear to those skilled in the ant may be madewithout departing from the scope of the invention. Reference is,therefore, to be had to the appended claims for a definition of thelimits of the invention.

What is claimed is:

1. In a rectifying circuit of a polarity reversible type for rectifyingan alternating current comprising a four pole double throw switchincluding two outer rows and an inner row of contacts, of four contactseach, and a four blade switch alternately operable for connecting eachcontact of the inner row of contacts to the corresponding contact of oneor the other of the outer row contacts; a rectifier connected betweenthe first and second contact of one of the outer rows of contacts; acapacitor connected between the third and fourth contacts of said oneouter row of contacts; a first conductor connected from the firstcontact of said one outer row to the second contact of the other outerrow; a second conductor connected from the first contact of said otherouter row to the second contact of said one outer row, a third conductorconnected from the third contact of said one outer row to the fourthcontact of said other outer row; a fourth conductor connected from thethird contact of said other outer row to the fourth contact of said oneouter row; a fifth conductor connected between the second and thirdcontacts of said inner row, and a direct current output conductor forsaid rectifier leading from said fifth conductor; an alternating currentinput conductor for said rectifier leading to the first contact of theinner row of contacts; a conductor providing both an alternating currentinput to said rectifier and a direct current output from said rectifierleading to the fourth contact of the inner row of contacts, saidrectifier upon an alternate operation of the switch from a positionclosing said one outer row of contacts to a position closing said otherouter row of contacts during the application of an alternating currentacross said input conductors, there is effected across the directcurrent output conductors an immediate reversal of polarity withoutsurging transient current and an operation in which the capacitor isretained in a continuous charged condition.

2. In a rectifying circuit of a polarity reversible type for rectifyingan alternating current comprising an operator-operative switch means, arectifier, and a capacitor, said capacitor and rectifier being seriallyconnected in operative relation with said switch means, said switchmeans being selectively operable to reverse the series connection ofsaid capacitor and rectifier in said operative relation with said switchmeans, a first conductor to said switch means providing a direct currentoutput for said rectifier, a second conductor to said switch meansproviding an alternating current input for said rectifier, a thirdconductor to said switch means providing both an alternating currentinput to said rectifier and a direct current output from said rectifier,said rectifier upon the selective operation of said switch means duringthe application of an alternating current across said input conductorscausing an immediate reversal of polarity in the direct current appliedthrough said output conductors while the capacitor is retained in acontinuous charged condition so as to prevent a transient surge in thedirect current at the output conductors upon said reversal in thepolarity thereof.

3. In a rectifying circuit of a polarity reversible type for rectifyingan alternating current, said circuit including a rectifier having inputand output conductors, a capacitor connected in series with saidrectifier, and to a conductor common to the input and output of saidrectifier, means for applying an alternating current to the inputconductor of said rectifier so as to provide a direct current at theoutput conductor of said rectifier, and means for reversing the polarityof the direct current applied through the rectifier to the outputconductors, and said reversing means including means for simultaneouslyreversing the series connection of the capacitor with said rectifier,and said capacitor being retained in a charged condition so as toprevent surging transient current upon a reversal in the polarity ofsaid direct current at the output conductors.

References Cited by the Examiner UNITED STATES PATENTS 2,129,783 9/1938Penney 321-15 X 2,637,010 4/1953 Charske 307-109 X 3,048,766 8/1962Pcnzer 321-8 X 3,164,747 1/1965 Yahnke 3l78 X MILTON O. HIRSHFIELD,Primary Examiner. LLOYD MCCOLLUM, Examiner.

1. IN A RECTIFYING CIRCUIT OF A POLARITY REVERSIBLE TYPE FOR RECTIFYINGAN ALTERNATING CURRENT COMPRISING A FOUR POLE DOUBLE THROW SWITCHINCLUDING TWO OUTER ROWS AND AN INNER ROW OF CONTACTS, OF FOUR CONTACTSEACH, AND A FOUR BLADE SWITCH ALTERNATELY OPERABLE FOR CONNECTING EACHCONTACT OF THE INNER ROW OF CONTACTS TO THE CORRESPONDING CONTACT OF ONEOR THE OTHER OF THE OUTER ROW CONTACTS; A RECTIFIER CONNECTED BETWEENTHE FIRST AND SECOND CONTACT OF ONE OF THE OUTER ROWS OF CONTACTS; ACAPACITOR CONNECTED BETWEEN THE THIRD AND FOURTH CONTACTS OF SAID ONEOUTER ROW OF CONTACTS; A FIRST CONDUCTOR CONNECTED FROM THE FIRSTCONTACT OF SAID ONE OUTER ROW TO THE SECOND CONTACT OF THE OTHER OUTERROW; A SECOND CONDUCTOR CONNECTED FROM THE FIRST CONTACT OF SAID OTHEROUTER ROW TO THE SECOND CONTACT OF SAID ONE OUTER ROW, A THIRD CONDUCTORCONNECTED FROM THE THIRD CONTACT OF SAID ONE OUTER ROW TO THE FOURTHCONTACT OF SAID OTHER OUTER ROW; A FOURTH CONDUCTOR CONNECTED FROM THETHIRD CONTACT OF SAID OTHER OUTER ROW TO THE FOURTH CONTACT OF SAID ONEOUTER ROW; A FIFTH CONDUCTOR CONNECTED BETWEEN THE SECOND AND THIRDCONTACTS OF SAID INNER ROW, AND A DIRECT CURRENT OUTPUT CONDUCTOR FORSAID RECTIFIER LEADING FROM SAID FIFTH CONDUCTOR; AN ALTERNATING CURRENTINPUT CONDUCTOR FOR SAID RECTIFIER LEADING TO THE FIRST CONTACT OF THEINNER ROW OF CONTACTS; A CONDUCTOR PROVIDING BOTH AN ALTERNATING CURRENTINPUT TO SAID RECTIFIER AND A DIRECT CURRENT OUTPUT FROM SAID RECTIFIERLEADING TO THE FOURTH CONTACT OF THE INNER ROW OF CONTACTS, SAIDRECTIFIER UPON AN ALTERNATE OPERATION OF THE SWITCH FROM A POSITIONCLOSING SAID ONE OUTER ROW OF CONTACTS TO A POSITION CLOSING SAID OTHEROUTER ROW OF CONTACTS DURING THE APPLICATION OF AN ALTERNATING CURRENTACROSS SAID INPUT CONDUCTORS, THERE IS EFFECTED ACROSS THE DIRECTCURRENT OUTPUT CONDUCTORS AN IMMEDIATE REVERSAL OF POLARITY WITHOUTSURGING TRANSIENT CURRENT AND AN OPERATION IN WHICH THE CAPACITOR ISRETAINED IN A CONTINUOUS CHARGED CONDITION.